The invention relates to a device for adjusting capsule thread brakes in twisting machines, in particular two-for-one twisters with several twisting spindles, in which each of the capsule thread brakes, each arranged inside the hub of the bobbin carrier of the twisting spindles and provided with a brake cartridge supported between two brake rings positioned one above the other in the axial direction, may be adjusted in steps to different brake force values by axial displacement and rotation. The invention also relates to a device on a twisting machine, in particular a two-for-one twister, with at least one twisting spindle, which has a bobbin carrier and wherein a capsule thread brake with a cylindrical housing is arranged inside the hub of the bobbin carrier, through which the thread is passed in the axial direction and which on the thread outlet side has a first brake ring, on which a brake cartridge is supported, on the upper end of which a second brake ring sits. At least one of the brake rings is arranged on a cylindrical brake ring support movable in the axial direction within the housing. A pressure spring acts on the side of the brake ring support facing away from the brake ring and is supported on the housing with its respective other end.
Such a capsule thread brake for twisting machines is described in German Patent 1 510 860, for example. The capsule thread brakes have a brake cartridge with an upper and a lower sleeve, which are joined onto one another so as to be freely movable and have a pressure spring enclosed between them. In the known capsule thread brake, the brake force is adjusted manually, whereby the brake ring support is raised in the axial direction against the bias of the pressure spring, rotated around its axis by a specific angle and then lowered by the action of the pressure spring into a new position, in which the support stop rests on one of the support shoulders arranged at different axial heights inside one of the axial slots. This brake force adjustment must be carried out manually on each individual twisting spindle in a twisting machine.
Thread brakes are also known, which may be adjusted centrally at the same time. However, these brakes are, for example, in the form of disc brakes (see Swiss Patent 636 577) which are actuated by compressed air.
A device for controlling thread brakes on a two-for-one twister is also known (see German Patent 1 510 853), in which a thread brake can be operated by means of an electromagnetic control device acting through the circulating thread balloon. In one embodiment of this known thread brake, an oval brake sleeve sits between two brake rings, one of which is mounted to move axially on an elastically expandable bellows which is filled with a fluid medium and connected via a pipe to a further bellows, which is filled with the same medium and on which a pressure is exerted by means of the electromagnetic control device. The pressure is transferred to the first bellows, thus applying a pressure to the axially movable brake body which results in an increase in the brake force. However, in this known device, which may also be actuated centrally, the brake force can only be adjusted within narrow limits.
It is therefore an object of the present invention to provide in a twisting machine of the aforementioned kind central actuation of the capsule thread brake, which should be structurally simple and operationally reliable in association with a large manufacturing range.